Fuel gas-oxygen cutting torches are well known and generally comprise a torch head having outlet passages communicating with a torch tip through which a combustible gaseous mixture flows and is ignited and directed toward a workpiece. The torch typically includes fuel gas and oxygen supply lines connected to corresponding sources of fuel gas and oxygen, and valves are provided for controlling the flow of fuel gas and oxygen to the torch head. Such torches have a preheat mode of operation in which the fuel gas and oxygen are combined in a mixer to provide a combustible mixture which then flows to the torch head outlet and torch tip where the mixture is ignited to form a preheat flame which is used to heat a workpiece to a temperature which will support combustion. Such torches also have a cutting mode of operation in which, following a preheat operation, cutting oxygen is supplied to the torch tip separate from the preheat combustible mixture to flow from the tip and cut the heated work piece.
It is the function of the fuel gas-oxygen mixer to mix the fuel gas and oxygen components—which are separately supplied thereto—and to deliver the mixture to the torch tip in order to achieve uniform combustion efficiency throughout the flame that results from igniting the combustible mixture at the tip.
Another performance requirement with regard to fuel gas-oxygen mixers is to provide resistance to flashback that can result from a backfire occurring, for example, in response to contacting the torch tip with the work piece. Such backfires can cause an explosion inside the torch between the point of mixing of the fuel gas and oxygen and the point of combustion of the mixture at the torch tip. Where backfiring results in sustained combustion inside the torch, this sustained combustion is defined as flashback. Flashback can quickly destroy a torch and injure a user. Accordingly, the fuel gas-oxygen mixer must be capable of minimizing or eliminating backfires so as to minimize the chance for, or impact of, flashbacks. Mixer designs heretofore available have been structurally complex, bulky, and undesirably expensive to manufacture. They are also difficult and/or time consuming to manufacture and assemble.
Moreover, many mixer designs suffer from the deficiency that they are limited to use with a single type of fuel (e.g., acetylene, natural gas, propane, propylene qtane). It would be desirable, therefore, to provide a simplified mixing head design that is easy to manufacture, that provides a desirable resistance to backfires/flashbacks and that is operable with a variety of fuels.